1. Field of the Invention
The present invention relates to an opening and closing device.
2. Description of Related Art
Conventionally, an opening and closing device includes a detector for detecting an existence of an object between a body of a vehicle and a door panel, which is in closing operation. Here, the opening and closing device uses a drive force of, for example, a motor to slidably displace (open and close) the door panel, which is provided on a side of a vehicle, along a longitudinal axis of the vehicle. For example, as JP-A-2004-257788 discloses, this type of detector includes a sensor electrode, which detects an object between a door panel and a body based on a change of a capacitance. The sensor electrode is disposed, for example, along a front end of a door panel. Also, in a case, where the object exists between the door panel and the body during a closing operation of the door panel for closing the door panel, the capacitance of the sensor electrode changes, and also the change of the capacitance is sent to a control unit of the detector as a signal voltage. The control unit, then, compares the received signal voltage and a predetermined threshold value. When the signal voltage exceeds the predetermined threshold value, the control unit determines that there is an object between the door panel and the body (determines the existence of the object between the door panel and the body), and the control unit displaces the door panel to a full open position using the drive force of the motor.
When the door panel in the closing operation approaches the full closed position, the front end of the door panel comes close to a front door and a center pillar (B pillar). Then, the proximity of the front end of the door panel to the front door and to the center pillar may cause a change of the capacitance of the sensor electrode, and therefore, the signal voltage may disadvantageously exceed the predetermined threshold value, resulting in an erroneous detection of the object. To deal with the above, conventionally, for example, when the door panel is located at a position of a predetermined distance away from the full closed position, the control unit adjusts the threshold value, and corrects the signal voltage sent by the detector in accordance with the change of the capacitance such that detectivity of the detector is set relatively lower to limit the erroneous detection of the object. Also, a constant threshold value may be set in an entire operational range of the door panel in consideration of the change of the capacitance due to the front door and the center pillar to limit the erroneous detection of the existence of the object.
However, in a case, where a threshold value is adjusted in accordance with a position of the door panel and the signal voltage is corrected to limit the erroneous detection of the object, a control process executed by the control unit for controlling the opening and closing device may disadvantageously become complex. Further, in another case, where a constant threshold value is set in an entire operational range of the door panel in consideration of the change of the capacitance due to the front door and the center pillar, the detectivity for detecting the object is also disadvantageously made lower even in other operational ranges of the door panel other than the range, where the capacitance is changed due to the front door.